Wire harnesses are large bundles of wire used to interconnect the electrical components of a vehicle to their respective controls and power source. The assembly of wire harnesses is a complex task. It is often not feasible to fully automate the assembly process due to the number of components and connectors being attached, the variety of harnesses assembled in a single factory, and the degree to which wire harnesses vary to accommodate different option packages within a given model vehicle.
An automated wire termination machine is problematic and includes a movable table, at least one die attached to the table, a cutting machine attached to the table, a payoff device for feeding the wire to the cutting machine, and a reel holder. The cutting machine cuts insulated wire into segments, strips the insulation off the ends of the wire segments. The reel holder includes a beam extending from the table, and a spindle rigidly attached to the beam. Typically, the terminals come in the form of strips on a reel. The reel is rotatably mounted on the spindle. The stripped ends of the wire segments and the strips of terminals are continuously fed to the die. The die crimps the terminal around the stripped end of the wire resulting in an electrically conductive connection between the two elements. The termination machine drops the completed wires into a tray. The wires are transported to an assembly area within the factory where the wires are laid onto a jig, and connected to other electrical components or arms of the wire harness by inserting the terminals into mating connectors. Typically the terminals are small delicate components.
Since the wires can get tangled during transportation within the factory, the operator prepares the wires for transportation by manually bundling the wires. First by aligning the ends of the wires in a flush manner, then using some material, such as film, to secure the ends together. Although bundling the wires in this way reduces tangling of the wires when they are moved, this method is problematic.
The terminals are small and include tabs for securing the terminals in mating the connectors. The tabs bend and break fairly easily. Since the film is wrapped over the terminals under tension, this causes deformation and damage to the terminals, which increases the costs of manufacturing. Furthermore, the materials used to secure the ends often are not biodegradable, thus not environmentally friendly. Some countries do not allow such materials to be disposed of there. The added cost of shipping this material elsewhere for disposal increases the operating costs of the factory. In addition, removing the material from the terminals can deform the tabs or unlatch the terminal, once either of these events occurs the terminal cannot be used because it will not meet the necessary requirements.
To ease the manual process of forming wire harnesses, stands are used in the assembly area to assist the worker in both separating and holding the wire supply during assembly. Typically these stands have separate areas for each type of wire, and allow the bundles of wires to be laid there so that the ends of the bundle are not in contact. After the bundles are transported to the proper assembly area, they are unwrapped, and placed on the stands. The assembly person removes each circuit as necessary during assembly by pulling the wire off the stand by the proximate end. This method is problematic because the distal end of the chosen wire must be pulled through all the other wires, which can cause the wires to tangle and/or cause deformation and damage to the distal terminals. In order to decrease tangles and damage to the terminals during assembly, the terminal least likely to tangle is placed at the distal end of the bundle. Although this orientation decreases tangles and damage, orienting the wires this way may decrease the efficiency of the operator since he may be required to rotate the circuit prior to use.
Therefore, an improved method for manufacturing wire harnesses and an improved device for holding wires during assembly are sought. These improvements minimizing tangling of the wires during assembly, decreasing the number of terminals damaged and deformed during manufacture, eliminating the use of wrapping materials, and allowing the wires to be held in an orientation which does not decrease the efficiency of the assembly person.